Mems sensor with side port and method of fabricating same

ABSTRACT

A MEMS sensor package comprises a MEMS die that includes a substrate having a sensor formed thereon and a cap layer coupled to the substrate. The cap layer has a cavity overlying a substrate region at which the sensor resides. A port extends between the cavity and a side wall of the MEMS die and enables admittance of fluid into the cavity. Fabrication methodology entails providing a substrate structure having sensors formed thereon, providing a cap layer structure having inwardly extending cavities, and forming a channel between pairs of the cavities. The cap layer structure is coupled with the substrate structure and each channel is interposed between a pair of cavities. A singulation process produces a pair of sensor packages, each having a port formed by splitting the channel, where the port is exposed during singulation and extends between its respective cavity and side wall of the sensor package.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to microelectromechanicalsystems (MEMS) sensor packages. More specifically, the present inventionrelates to a MEMS sensor with a side wall port to provide a path forpassage of an external fluid medium.

BACKGROUND OF THE INVENTION

Microelectromechanical systems (MEMS) devices are semiconductor deviceswith embedded mechanical components. MEMS devices include, for example,pressure sensors, accelerometers, gyroscopes, microphones, digitalmirror displays, micro fluidic devices, and so forth. MEMS devices areused in a variety of products such as automobile airbag systems, controlapplications in automobiles, navigation, display systems, inkjetcartridges, and so forth.

There are significant challenges to be surmounted in the packaging ofMEMS devices due at least in part to the necessity for the MEMS devicesto interact with the outside environment, the fragility of many types ofMEMS devices, and severe cost constraints. Indeed, many MEMS deviceapplications require smaller size and low cost packaging to meetaggressive cost targets.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures in which like reference numerals refer toidentical or functionally similar elements throughout the separateviews, the figures are not necessarily drawn to scale, and whichtogether with the detailed description below are incorporated in andform part of the specification, serve to further illustrate variousembodiments and to explain various principles and advantages all inaccordance with the present invention.

FIG. 1 shows a side sectional view of a microelectromechanical systems(MEMS) sensor package in accordance with an embodiment;

FIG. 2 shows a side sectional view of a structure that includes a firstintermediate sensor structure and a second intermediate sensor structureprior to singulation;

FIG. 3 shows a side sectional view of the structure of FIG. 2 followingsingulation;

FIG. 4 shows a side sectional view of a portion of the structure of FIG.2;

FIG. 5 shows a top view of a substrate structure that may be used toform the structure of FIG. 2;

FIG. 6 shows a bottom view of a cap layer structure that may be used toform the structure of FIG. 2;

FIG. 7 shows a side sectional view of a structure that includes a firstintermediate sensor structure and a second intermediate sensor structureprior to singulation in accordance with another embodiment;

FIG. 8 shows a side sectional view of a structure that includes a firstintermediate sensor structure and a second intermediate sensor structureprior to singulation in accordance with another embodiment;

FIG. 9 shows a side sectional view of a structure that includes a firstintermediate sensor structure and a second intermediate sensor structureprior to singulation in accordance with yet another embodiment; and

FIG. 10 shows a flowchart of a sensor package fabrication process inaccordance with another embodiment.

DETAILED DESCRIPTION

As the uses for microelectromechanical systems (MEMS) devices continueto grow and diversify, increasing emphasis is being placed on smallersize and low cost packaging without sacrificing part performance.Embodiments entail a MEMS sensor package and a method of fabricating theMEMS sensor package. In particular, the MEMS sensor package is formed,through the execution of relatively simple methodology, to include aMEMS sensor on a substrate that is covered by a cap layer. The MEMSsensor resides in a cavity formed in the cap layer, and a port extendsbetween the cavity and a side wall of one of the substrate and the caplayer. The pressure port formed in the side wall is exposed during astrip singulation operation of the methodology so that fluid, such asair, external to the cavity can be admitted into the cavity.

The instant disclosure is provided to explain in an enabling fashion thebest modes, at the time of the application, of making and using variousembodiments in accordance with the present invention. The disclosure isfurther offered to enhance an understanding and appreciation for theinventive principles and advantages thereof, rather than to limit in anymanner the invention. The invention is defined solely by the appendedclaims including any amendments made during the pendency of thisapplication and all equivalents of those claims as issued.

Referring to FIG. 1, FIG. 1 shows a side sectional view of amicroelectromechanical systems (MEMS) sensor package 20 in accordancewith an embodiment. FIG. 1 and subsequent FIGS. 2-8 are illustratedusing various shading and/or hatching to distinguish the differentelements of the MEMS sensor packages, as will be discussed below. Thesedifferent elements within the structural layers may be producedutilizing current and upcoming micromachining techniques of depositing,patterning, etching, and so forth. It should be further understood thatthe use herein of relational terms, if any, such as first and second,top and bottom, and the like are used solely to distinguish one fromanother entity or action without necessarily requiring or implying anyactual such relationship or order between such entities or actions.

MEMS sensor package 20 generally includes MEMS die 22 coupled to anapplication specific integrated circuit (ASIC), generally referred toherein as a semiconductor die 24. Semiconductor die 24, in turn, may becoupled to a mounting pad 26 of a carrier, referred to herein as a leadframe 28. MEMS die 22 includes a substrate 30 and a cap layer 32. In anembodiment, substrate 30 has a first inner surface 34 and a first outersurface 36. Similarly, cap layer 32 has a second inner surface 38 and asecond outer surface 40. Second inner surface 38 of cap layer 32 iscoupled to first inner surface 34 of substrate 30. A MEMS sensor 42 isformed on first inner surface 34 of substrate 30. More particularly, caplayer 32 includes a cavity 44 extending inwardly from second innersurface 38 and overlying a region 46 of first inner surface 34 ofsubstrate 30. MEMS sensor 42 resides in cavity 44 at region 46 of firstinner surface 34 of substrate 30.

One or both of substrate 30 and cap layer 32 includes a port 48extending between cavity 44 and a side wall 50 of MEMS die 22, whereside wall 50 extends between first outer surface 36 of substrate 30 andsecond outer surface 40 of cap layer 32. In the illustrated embodiment,port 48 is formed as a recess in second inner surface 38 of cap layer32. In other embodiments, port 48 may be formed as a recess in firstinner surface 34 of substrate 30. MEMS sensor 42 may be a pressuresensor having a pressure deformable diaphragm 52 disposed at region 46of first inner surface 34 of substrate 30. Port 48 is configured toadmit a fluid, e.g., air, from an environment external to cavity 44 intocavity 44. Since fluid can enter cavity 44 via port 48, MEMS pressuresensor 42 having pressure deformable diaphragm 52 can detect an ambientpressure 53, labeled P, of an environment external to MEMS sensorpackage 20.

MEMS die 22 further includes bond pads 54 on first inner surface 34 ofsubstrate 30, but external to cap layer 32, and conductive traces 56(shown in FIG. 5) interconnected between MEMS sensor 42 and bond pads54. Conductive traces 56 suitably electrically couple MEMS sensor 42with bond pads 54. Bond pads 54 may be utilized to electrically connectMEMS sensor 42 to bond pads 58 of semiconductor die 24 via electricallyconductive interconnects, or bond wires 60 in this example.Semiconductor die 24 may include additional bond pads 62 that may beutilized to electrically connect semiconductor die 24 to externalconnection leads 64 of lead frame 28 via electrically conductiveinterconnects, or bond wires 66 in this example. Leads 64 provide inputto and output from MEMS sensor package 20, as known to those skilled inthe art.

An encapsulant 68 covers, or encapsulates, MEMS die 22, semiconductordie 24, bond wires 60, bond wires 66, and the top surfaces of leads 64.Encapsulant 68 (e.g., a mold compound or protective resin system)protects the components of MEMS sensor package 20 from exposure toexternal elements (e.g., air, moisture, and/or liquids) to providerobust mechanical and environmental protection. It should be noted,however, that encapsulant 68 does not obstruct port 48 in side wall 50of MEMS sensor package 20. Fabrication methodology presented in detailherein enables the assembly of the components of MEMS sensor package 20and, in some embodiments, their encapsulation with encapsulant 68without obstructing port 48 in side wall 50.

Referring now to FIGS. 2 and 3, FIG. 2 shows a side sectional view of astructure 70 that includes a first intermediate sensor structure 72 anda second intermediate sensor structure 74 prior to singulation, and FIG.3 shows a side sectional view of structure 70 following singulation.First intermediate sensor structure 72 is laterally displaced fromsecond intermediate sensor structure 74 within structure 70.Additionally, each of first and second intermediate sensor structures72, 74 includes the structural components described in connection withFIG. 1. That is, each of first and second intermediate sensor structures72, 74 includes MEMS die 22, semiconductor die 24, lead frame 28, andbond wires 60, 66 all of which are covered in encapsulant 68. Furtherdescription of MEMS die 22, semiconductor die 24, lead frame 28, andbond wires 60, 66 of first and second intermediate sensor structures 72,74 is not repeated herein for brevity.

In accordance with a particular embodiment, first and secondintermediate sensor structures 72, 74 of structure 70 are interconnectedvia inactive/unused material regions 76 of each of a cap layer structure78, a substrate structure 80, a semiconductor die structure 82, and astrip 84 of lead frames 28. Structure 70 further includes a channel 86interposed between cavity 44 of first intermediate sensor structure 72and cavity 44 of second intermediate sensor structure 74. Thus, cavity44 of first intermediate sensor structure 72 and cavity 44 of secondintermediate sensor structure 74 are in fluid communication with oneanother.

First intermediate sensor structure 72 is configured to be separatedfrom second intermediate sensor structure 74 to produce a first MEMSsensor package, referred to herein as a first pressure sensor package20A (FIG. 3), and to produce a second MEMS sensor package, referred toherein as a second pressure sensor package 20B (FIG. 3). That is,structure 70 may be sawn, diced, or otherwise singulated atinactive/unused material regions 76 bounded by dashed lines 88 in orderto remove the material portion of structure 70 between dashed lines 88.

Following singulation, each of first and second pressure sensor packages20A, 20B includes the structural components described in connection withFIG. 1. That is, each of first and second sensor packages 20A, 20Bincludes MEMS die 22, semiconductor die 24, lead frame 28, and bondwires 60, 66 all of which are covered in encapsulant 68. The letter “A”is used in FIG. 3 to denote the elements of first pressure sensorpackage 20A and the letter “B” is used herein to denote the elements ofsecond pressure sensor package 20B for clarity of description. It shouldbe observed that the singulation process separates channel 86 into tworemaining portions. Thus, a first port 48A of first pressure sensorpackage 20A is a first portion of channel 86 and a second port 48B ofsecond pressure sensor package 20B is a second portion of channel 86.

Referring to FIGS. 4 and 5, FIG. 4 shows a side sectional view of a MEMSdie structure 89 that is part of structure 70 (FIG. 2), and FIG. 5 showsa top view of substrate structure 80 that may be used to form structure70. More particularly, MEMS die structure 89 of FIG. 4 includes caplayer structure 78 coupled with substrate structure 80 to form a pair ofMEMS dies 22. However, it should be observed that FIG. 4 does notinclude semiconductor dies 24 (FIG. 2) and lead frames 28 (FIG. 2). FIG.5 shows substrate structure 80 with cap layer structure 78 absent inorder to reveal the features of substrate structure 80.

In general, substrate structure 80 includes a bulk substrate 88 and astructural layer 90 fixed to a surface 92 of bulk substrate 88. MEMSsensors 42 are formed on, or alternatively in, structural layer 90. Asshown, sets of bond pads 54 and conductive traces 56 are also formed onstructural layer 90. Substrate structure 80 is shown with only two MEMSsensors 42 for simplicity of illustration. It should be understood,however, that substrate structure 80 can include multiple MEMS sensors42 arranged in pairs (as shown) in a high volume manufacturingconfiguration.

In accordance with an example embodiment, bulk substrate 88 has recesses94 extending inwardly from surface 92 of bulk substrate 88, andstructural layer 90 is fixed to surface 92 of bulk substrate 88surrounding recesses 94. Material portions of structural layer 90 areremoved surrounding each of MEMS sensors 42 to form cantileveredplatform structures 96 at which each of MEMS sensors 42 reside. Thus,cantilevered platform structures 96 are formed in structural layer 90and each extends over a respective one of recesses 94.

Each of cantilevered platform structures 96 includes a platform 98 andan arm 100 extending from platform 98. One end of arm 100 is fixed toplatform 98 and the other end of arm 100 is fixed to bulk substrate 88via an attachment of arm 100 to a portion of structural layer 90 fixedto surface 92 of bulk substrate 88 surrounding recess 94. Thus, once thematerial portions of structural layer 90 are removed, openings 102extend through structural layer 90 and partially surround cantileveredplatform structures 96. Accordingly, platforms 98 and arms 100 aresuspended over recesses 94, with an end of each of arms 100 being thesole attachment point of each of cantilevered platform structure 96 tothe surrounding bulk substrate 88. Although each of cantileveredplatform structures 96 includes an arm 100 which forms a sole attachmentpoint to the surrounding bulk substrate 88, other configurations mayinclude more than one attachment point to the surrounding bulksubstrate.

The illustrated configuration yields MEMS sensors 42 each of which isformed on a cantilevered platform structure 96 that is suspended over arecess 94. The cantilevered platform structure can achieve the benefitsof improved package stress isolation and improved device performance,especially for pressure sensor configurations. However, it should beunderstood that alternative embodiments need not include thatcantilevered platform structures overlying recesses. Instead, someembodiments may include MEMS sensors that are formed on a solidsubstrate (i.e., do not have recesses) and reside in cavities 44, butstill require porting to an external environment via port 48 (FIG. 1) inside wall 50 (FIG. 1).

Referring now to FIGS. 4 and 6, FIG. 6 shows a bottom view of cap layerstructure 78 that may be used to form structure 70 (FIG. 2). Cap layer78 includes two cavities 44 and channel 86 extending inwardly from asurface 104 of cap layer structure 78. Cap layer structure 78 is shownwith only two cavities 44 formed therein to correspond with substratestructure 80 (FIG. 5) and for simplicity of illustration. It should beunderstood, however, that cap layer structure 78 can include multiplecavities 44 arranged in pairs with channels 86 extending between pairsof cavities 44 in a high volume manufacturing configuration.

In general, cap layer structure 78 may be coupled with substratestructure 80 via a bond material 106, where bonding may be, for example,glass frit bonding, aluminum-germanium bonding, copper-to-copperbonding, or any other suitable bonding process and bonding material.Bond material 106 may be suitably located between cap layer structure 78and substrate structure 80 outside of the boundaries of cavities 44 andchannel 86. In some embodiments, when cap layer structure 78 is coupledwith substrate structure, material portions 108 overlie bond pads 54.Thus, a saw-to-reveal process may be performed to expose bond pads 54from cap layer structure 78. That is, following coupling with substratestructure 80, cap layer structure 78 may be sawn along saw lines(represented by dashed lines 110) shown in FIG. 6 to remove materialportions 108 and thereby expose bond pads 54. As such, bond material 106may be limited to those regions between saw lines 110 so as not to comein contact with bond pads 54. In other embodiments, bond material 106may not be limited to the regions between saw lines 110. As such,following a saw-to-reveal process, bond material 106 may be removed frombond pads 54.

FIG. 7 shows a side sectional view of a structure 112 that includes afirst intermediate sensor structure 114 and a second intermediate sensorstructure 116 prior to singulation in accordance with anotherembodiment. Structure 112 is similar to structure 70 (FIG. 2) describedabove. Thus, structure 112 includes cap layer structure 78, substratestructure 80, and strip 84 so that each of first and second intermediatesensor structures 114, 116 includes MEMS die 22, lead frame 28, and bondwires 60, 66 all of which are covered in encapsulant 68. However, inlieu of semiconductor die structure 82 (FIG. 2), structure 112 isfabricated utilizing previously singulated semiconductor dies 24 thatare suitably coupled to strip 84. The resulting encapsulated structure112 is singulated and channel 86 is split to expose the two ports 48A,48B to the external environment, as discussed above.

FIG. 8 shows a side sectional view of a structure 118 that includes afirst intermediate sensor structure 120 and a second intermediate sensorstructure 122 prior to singulation in accordance with anotherembodiment. Structure 118 is similar to structure 70 (FIG. 2). Thus,structure 118 includes cap layer structure 78, semiconductor diestructure 82, strip 84, and bond wires 66 all of which are covered inencapsulant 68. However, in lieu of substrate structure 80 (FIG. 2),structure 118 is fabricated utilizing a substrate structure 124 thatincludes many of the elements described above including MEMS sensors 42.However, substrate structure 124 includes electrically conductiveinterconnects in the form of electrically conductive vias 126 extendingthrough a bulk substrate 128 of substrate structure in lieu of bondwires 60 (FIG. 2). Conductive vias 126 can thus form the electricalconnections between MEMS sensors 42 and semiconductor dies 24 ofsemiconductor die structure 82.

Such a structural configuration eliminates the need for bond wiresbetween the MEMS sensor and the underlying semiconductor die which mayreduce packaging size and complexity. The resulting encapsulatedstructure 118 is singulated and channel 86 is split to expose the twoports 48A, 48B to the external environment, as discussed above.

FIG. 9 shows a side sectional view of a structure 130 that includes afirst intermediate sensor structure 132 and a second intermediate sensor134 structure prior to singulation in accordance with yet anotherembodiment. Structure 130 includes cap layer structure 78 and substratestructure 124 having electrically conductive vias 126 extending throughit. Structure 130 further includes a semiconductor die structure 136having electrically conductive vias 138 extending through it.Electrically conductive vias 138 are provided in lieu of bond wires 66(FIG. 2) and lead frame 28 (FIG. 2) and enable input to and output fromthe resulting MEMS sensor packages.

Since conductive vias 126 are internal to substrate structure 124 andconductive vias 138 are internal to semiconductor die structure 136, theresulting package need not be encapsulated in encapsulant 68 (FIG. 1).Furthermore, savings may be achieved in terms of the packagingcomplexity and overall size of the resulting MEMS sensor packages. Theresulting structure 130 is singulated and channel 86 is split to exposethe two ports 48A, 48B to the external environment, as discussed above.

Now referring to FIG. 10, FIG. 10 shows a flowchart of a sensor packagefabrication process 140 in accordance with another embodiment. Themethodology entails fabrication of side oriented ports (for example,pressure ports) into the silicon that are exposed at strip singulation.Sensor package fabrication process 140 will be described in connectionwith the fabrication of two MEMS sensor packages 20A, 20B (FIG. 3) shownin detail in FIGS. 1-6 for simplicity of illustration. However it shouldbe apparent to those skilled in the art that the ensuing methodology maybe executed to concurrently fabricate more than two MEMS sensor packages20 in a high volume manufacturing environment. Additionally, it shouldbe understood that sensor package fabrication process 140 may be adaptedto produce any of the MEMS sensor package configurations alternativelydescribed in connection with FIGS. 7-9 above.

The ordering of process operations presented below in connection withsensor package fabrication process 140 should not be construed aslimiting, but is instead provided as an example of a possiblefabrication method that may be implemented. Furthermore, it will beunderstood by those skilled in the art that the following processoperations may be executed in a different order than presented below.

Sensor package fabrication process 140 includes process blocks relatedto the fabrication of MEMS die structure 89 (FIG. 4) having MEMS sensors42 formed therein. These process blocks are delineated by a largerdashed line box and include blocks 142, 144, and 146. At block 142 ofsensor package fabrication process 140, substrate structure 80 isprovided having MEMS sensors 42 formed thereon. At block 144, cap layerstructure 78 (FIGS. 4 and 6) is provided, with cavities 44 and channel86 being formed in cap layer 78. At block 146, cap layer 78 is coupledto substrate structure 80 via bond material 106 to form MEMS diestructure 89. As mentioned previously, bonding may be performed usingany other suitable bonding process and material.

At a block 148, semiconductor die structure 82 containing semiconductordies 24 may be coupled to strip 84 (FIG. 2) of lead frames 28 in someembodiments. Of course, in configurations that do not include a leadframe (e.g., structure 130 of FIG. 9), block 148 need not be performed.At a block 150, MEMS die structure 89 formed in accordance with processblocks 142, 144, 146 is coupled with semiconductor die structure 82using, for example, a die attach adhesive.

At a block 152, the electrically conductive interconnects may be formed.Referring to FIG. 2, bond wires 60 may be formed between substratestructure 80 and semiconductor die structure 82. Additionally, bondwires 66 may be formed between semiconductor die structure 82 andexternal connection leads 64 of lead frames 28. Referring to FIG. 8, inconfigurations that do not include bond wires 60 (e.g., structure 118),the electrically conductive interconnects in the form of conductive vias126 will be formed during fabrication of substrate structure 124 and theelectrically conductive interconnects in the form of bond wires 66 willbe formed after semiconductor die structure 82 is coupled to strip 84 oflead frames 28. Referring now to FIG. 9, in still other configurationsthat do not include any bond wires 60, 66 (e.g., structure 130), theelectrically conductive interconnects in the form of conductive vias 126will be formed during fabrication of substrate structure 124 and theelectrically conductive interconnects in the form of vias 138 will beformed during fabrication of semiconductor die structure 136.

At a block 154, strip 84, semiconductor die structure 82, substratestructure 80, cap layer 78, and bond wires 60, 66 are encapsulated(i.e., covered) in encapsulant 68. Referring to FIGS. 2, 7, and 8, theside oriented channel 86 that will become ports 48A, 48B followingsingulation is protected from encapsulant 68. In configurations that donot include encapsulant 68 (e.g., structure 130 of FIG. 9), block 154need not be performed.

Some prior art structures call for the bond wires to pass through a gelcoating. The gel coating is prone to bubble formation and can causeflexing of the bond wires. Bubble formation and flexing of the bondwires can cause the parasitic capacitances between neighboring wires tochange, thus adversely affecting the sensor offset. In accordance withthe embodiments described herein, since bond wires 60 and bond wires 66are encapsulated (FIGS. 2 and 6) in encapsulant 68 and/or through theuse of conductive vias 126 (FIG. 7), the bond wires advantageously neednot pass through the gel coating.

Following encapsulation block 154, a process block 156 is performed. Atblock 156, a singulation process (e.g., wet sawing, laser cutting, orthe like) may be performed to separate the over molded structure intothe individual first and second sensor packages 20A, 20B and to exposeports 48A, 48B. In cases in which the structure may be damaged by debrisentering cavities 44 via ports 48A, 48B by conventional singulationtechniques, singulation may be performed using a stealth dicingtechnique, by using a two step dicing operation to clear out anyelectrically conductive material produced by a first dicing operationprior to performing the second dicing operation, or any other techniquewhich largely prevents or limits the entry of debris into cavities 44via ports 48A, 48B.

Following block 156, sensor package fabrication process 140 endsfollowing the production of multiple MEMS sensor packages, each of whichincludes a side port extending between a cavity and a side wall of thesensor package. The side port is configured to admit a fluid, e.g., air,external to the cavity into the cavity. When the MEMS sensor packageincludes a pressure sensor, the pressure of the fluid entering thecavity can be suitably detected by the pressure sensor.

An embodiment of a MEMS sensor package comprises a MEMS die, said MEMSdie comprising a substrate having a first inner surface and a firstouter surface, a MEMS sensor formed on the first inner surface, and acap layer having a second inner surface and a second outer surface. Thesecond inner surface of the cap layer is coupled to the first innersurface of the substrate. The cap layer includes a cavity extendinginwardly from the second inner surface and overlying a region of thefirst inner surface of the substrate. The MEMS sensor resides in thecavity at the region of the first inner surface of the substrate, andone of the substrate and the cap layer includes a port extending betweenthe cavity and a side wall of the MEMS die, where the side wall extendsbetween the first outer surface of the substrate and the second outersurface of the cap layer.

An embodiment of a method of making MEMS sensor packages comprisesproviding a substrate having a first inner surface and a second outersurface, the substrate including a first MEMS sensor at a first regionof the first inner surface and a second MEMS sensor at a second regionof the first inner surface, the second region being laterally displacedfrom the first region, and providing a cap layer having a second innersurface and a second outer surface, the cap layer including a firstcavity and a second cavity laterally displaced from the first cavity,each of the first and second cavities extending inwardly from the secondinner surface. A channel is formed extending inwardly from one of thefirst inner surface of the substrate and the second inner surface of thecap layer. The second inner surface of the cap layer is coupled to thefirst inner surface of the substrate such that the first cavity overliesthe first region to form a first intermediate sensor structure, thesecond cavity overlies the second region to form a second intermediatesensor structure, and the channel is interposed between the first andsecond cavities such that the first and second cavities are in fluidcommunication with one another. The first intermediate sensor structureis separated from the second intermediate sensor structure to produce afirst MEMS sensor package and a second MEMS sensor package.

An embodiment of a structure comprises a substrate having a first innersurface and a first outer surface, a MEMS pressure sensor formed on thefirst inner surface, a cap layer having a second inner surface and asecond outer surface, and an encapsulant covering the substrate and thecap layer, wherein the second inner surface of the cap layer is coupledto the first inner surface of the substrate, the cap layer includes acavity extending inwardly from the second inner surface and overlying aregion of the first inner surface of the substrate, the MEMS pressuresensor resides in the cavity and includes a pressure deformablediaphragm disposed at the region of the first inner surface of thesubstrate, one of the substrate and the cap layer includes a portextending between the cavity and a side wall of the cap layer, the sidewall extending between the first outer surface of the substrate and thesecond outer surface of the cap layer, and the encapsulant does notobstruct the port.

Thus, a MEMS sensor package is formed, through the execution ofrelatively simple methodology, to include a MEMS sensor on substratethat is covered by a cap layer. The MEMS sensor resides in a cavityformed in the cap layer, and a port extends between the cavity and aside wall of one of the substrate and the cap layer. The port, formed inthe side wall, is exposed during a strip singulation operation of themethodology so that fluid, such as air, external to the cavity can beadmitted into the cavity. Accordingly, the MEMS sensor may be a pressuresensor which is stress isolated and can be overmolded, and the pressuresensor is capable of sensing pressure from an environment external tothe sensor via the port.

This disclosure is intended to explain how to fashion and use variousembodiments in accordance with the invention rather than to limit thetrue, intended, and fair scope and spirit thereof. The foregoingdescription is not intended to be exhaustive or to limit the inventionto the precise form disclosed. A vast number of variations ormodifications are possible in light of the above teachings. Theembodiment(s) was chosen and described to provide the best illustrationof the principles of the invention and its practical application, and toenable one of ordinary skill in the art to utilize the invention invarious embodiments and with various modifications as are suited to theparticular use contemplated. All such modifications and variations arewithin the scope of the invention as determined by the appended claims,as may be amended during the pendency of this application for patent,and all equivalents thereof, when interpreted in accordance with thebreadth to which they are fairly, legally, and equitably entitled.

1. A microelectromechanical systems (MEMS) sensor package comprising: aMEMS die, said MEMS die comprising: a substrate having a first innersurface and a first outer surface; a MEMS sensor formed on said firstinner surface; and a cap layer having a second inner surface and asecond outer surface, wherein said second inner surface of said caplayer is coupled to said first inner surface of said substrate, said caplayer includes a cavity extending inwardly from said second innersurface and overlying a region of said first inner surface of saidsubstrate, said MEMS sensor resides in said cavity at said region ofsaid first inner surface of said substrate, and a port extends betweensaid cavity and a side wall of said MEMS die, said side wall extendingbetween said first outer surface of said substrate and said second outersurface of said cap layer; and an encapsulant covering said MEMS die,wherein said encapsulant is absent from said side wall and saidencapsulant does not obstruct said port.
 2. The MEMS sensor package ofclaim 1 wherein said port is configured to admit a fluid external tosaid cavity into said cavity.
 3. (canceled)
 4. The MEMS sensor packageof claim 1 wherein said substrate has a recess formed therein, and saidMEMS die further comprises a cantilevered platform structure having aplatform and an arm extending from said platform, wherein said platformand said arm are suspended over said recess, said arm is fixed to saidsubstrate, and said platform includes said region at which said MEMSsensor resides.
 5. The MEMS sensor package of claim 4 wherein said armis a sole attachment point of said platform to said substrate.
 6. TheMEMS sensor package of claim 1 further comprising a semiconductor diecoupled to one of said first outer surface of said substrate and saidsecond outer surface of said cap layer.
 7. The MEMS sensor package ofclaim 6 further comprising conductive interconnects electricallycoupling said MEMS sensor with said semiconductor die.
 8. The MEMSsensor package of claim 1 wherein said MEMS sensor comprises a pressuresensor, said pressure sensor including a pressure deformable diaphragmdisposed at said region of said first inner surface of said substrate.9-17. (canceled)
 18. A structure comprising: a substrate having a firstinner surface and a first outer surface; a MEMS pressure sensor formedon said first inner surface; a cap layer having a second inner surfaceand a second outer surface; and an encapsulant covering said substrateand said cap layer, wherein: said second inner surface of said cap layeris coupled to said first inner surface of said substrate; said cap layerincludes a cavity extending inwardly from said second inner surface andoverlying a region of said first inner surface of said substrate; saidMEMS pressure sensor resides in said cavity and includes a pressuredeformable diaphragm disposed at said region of said first inner surfaceof said substrate; a port extends between said cavity and a side wall ofsaid cap layer, said side wall extending between said first outersurface of said substrate and said second outer surface of said caplayer; said encapsulant is absent from said side wall; and saidencapsulant does not obstruct said port.
 19. The structure of claim 18wherein said port is configured to admit a fluid external to said cavityinto said cavity.
 20. The structure of claim 18 wherein said MEMSpressure sensor is a first MEMS pressure sensor, said region is a firstregion, said cavity is a first cavity, said port is a first port, saidside wall is a first side wall, said first MEMS pressure sensor residingin said first cavity is a first intermediate sensor structure and: saidstructure comprises a second MEMS pressure sensor at a second region ofsaid first inner surface, said second region being laterally displacedfrom said first region; and said cap layer includes a second cavitylaterally displaced from said first cavity, wherein: said second cavityextends inwardly from said second inner surface and overlies a secondregion of said first inner surface; said second MEMS pressure sensorresides in said second cavity at said second region of said first innersurface of said substrate to form a second intermediate sensorstructure; a channel extends inwardly from said second inner surface ofsaid cap layer, said channel being interposed between said first andsecond cavities; said first intermediate sensor structure is configuredto be separated from said second intermediate sensor structure toproduce a first MEMS pressure sensor package that includes said firstMEMS pressure sensor having said first port and to produce a second MEMSpressure sensor that includes said second MEMS pressure sensor having asecond port, said first port being a first portion of said channel, saidsecond port being a second portion of said channel; and said second portextends between said second cavity and a second side wall of said secondMEMS sensor package, said second side wall extending between said firstouter surface of said substrate and said second outer surface of saidcap layer.